This invention is concerned with a method of determining the quality of a lubricant layer on a surface of a magnetic recording medium particularly magnetic recording media used as fixed disk auxiliary storage devices for information processing systems. Conventional magnetic recording media of this type typically are formed from a nonmagnetic substrate, a magnetic layer, a protective layer, for example of carbon, and a lubricant layer. The lubricating layer and the protective layer together are intended to provide the environmental resistance, wear resistance and lubricity necessary in a device of this type. It is therefore important that the lubricating layer provide an effective and consistent surface upon which the magnetic recording head can ride. In many cases, however, this is not obtained.
Lubricant layers (particularly fluorocarbon lubricants) formed on a carbon protective layer of a magnetic recording medium may be defective as a result of uneven lubricating properties of the lubricant layer. When such unevenness is present, the friction coefficient of the lubricant layer with respect to a magnetic head is so small that it is difficult to stably obtain a good lubricating property which would minimize the "sticking" of the magnetic head to the recording medium. Heretofore, however, there has been no way to quantitatively test the quality of the lubricant layer short of a long term wear test. It is an object of the present invention to provide such a method.